Juniper Networks EX8208 - Manual (Page 322)

DC Power Electrical Safety Guidelines for EX Series Switches
The following electrical safety guidelines apply to a DC-powered switch:
• A DC-powered switch is equipped with a DC terminal block that is rated for the power
requirements of a maximally configured switch.
NOTE: To supply sufficient power, terminate the DC input wiring on a facility DC source
capable of supplying at least 8 A at –48 VDC for EX3200 and EX4200 switches.
To supply sufficient power, terminate the DC input wiring on a facility DC source capable
of supplying at least 60 A at –48 VDC for EX8208 switches.
To supply sufficient power, terminate the DC input wiring on a facility DC source capable
of supplying at least 100 A at –48 VDC for EX8216 switches.
Incorporate an easily accessible disconnect device into the facility wiring. Be sure to
connect the ground wire or conduit to a solid office earth ground. A closed loop ring is
recommended for terminating the ground conductor at the ground stud.
• Run two wires from the circuit breaker box to a source of 48 VDC.
• A DC-powered router that is equipped with a DC terminal block is intended only for
installation in a restricted access location. In the United States, a restricted access
area is one in accordance with Articles 110-16, 110-17, and 110-18 of the National Electrical
Code ANSI/NFPA 70.
NOTE: Primary overcurrent protection is provided by the building circuit breaker. This
breaker must protect against excess currents, short circuits, and earth grounding faults
in accordance with NEC ANSI/NFPA 70.
• Ensure that the polarity of the DC input wiring is correct. Under certain conditions,
connections with reversed polarity might trip the primary circuit breaker or damage
the equipment.
• For personal safety, connect the green and yellow wire to safety (earth) ground at both
the switch and the supply side of the DC wiring.
• The marked input voltage of –48 VDC for a DC-powered switch is the nominal voltage
associated with the battery circuit, and any higher voltages are only to be associated
with float voltages for the charging function.
• Because the switch is a positive ground system, you must connect the positive lead to
the terminal labeled RTN, the negative lead to the terminal labeled –48 VDC, and the
earth ground to the chassis grounding points.
Related Topics General Safety Guidelines and Warnings for EX Series Switches on page 263 •
• General Electrical Safety Guidelines and Warnings for EX Series Switches on page 291
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